Flashing lamp



Oct. 31,1944. w MacGREGOR 2,361,485

FLASHING LAMP Filed Jan. 26, 1944 Inveni'or: (WiLLiam F. MacGvegoY,

His A tforneg.

Patented Oct. 31, 1944 1 FLASHING LAMP William F. MacGregor, Toronto, Ontario, Canada,

assignor to General Electric Company,'a corporation of New York Application January 26, 1944, Serial No. 519,765 In Canada March 26, 1943 4 Claims.

My invention relates to incandescent-electric lamps and particularly to lamps arranged to have the filament automatically energized intermittentiy.

For many purposes it is desirable to have an incandescent lamp which flashes intermittently. For example in battery operated lamps used for signalling purposes on life preservers, buoys and the like, a flashing light is desirable not only on account of its greater conspicuousness but also on account of longer battery and lamp life which is obtained.

My invention provides a means incorporated in the lamp itself as a permanent part thereof whereby the current through the filament is intermittently interrupted and completed and provides a lamp of simple, reliable construction which can be inserted in standard sockets and flashed intermittently without the use of additional apparatus.

In accordance with my invention I mount a bimetallic stripon supports extending from the lamp stem and arranged in such a manner with respect to the lamp filament, that when the filament is cold the circuit therethrough is complete but when influenced by the heat from the filament the circuit therethrough is interrupted,

For a complete understanding of my invention reference is made to the following detailed description of an embodiment thereof together with the accompanying drawing. In the drawing Fig. 1 is a perspectiveview of a lamp of my invention; and Fig. 2 is a view looking down on the top of the elements.

As shown in the drawing the incandescent lamp comprises an exhausted glass bulb H), which encloses a hollow vitreous stem l3. Current leadin wires l4 and I5 inside the hollow stem enter the bulb l through the seal or press 13' at the upper end thereof. The lead-in wires are electrically connected to the usual shell contact ll and-center contact l2 of the base respectively as is shown in dotted lines in Fg, 1. The leading-in conductor l extends upwardly from the stem and is formed with a bend IB at its upper end which lies in a plane at right angles to the stem. An additional support or contact wire 11 anchored in the stem I3 also extends upwardly and has its upper end l8 bent to lie at r'ght angles to the stem. The end I! lies parallel to and spaced from the end It of the lead-in wire and support IS. A narrow strip of bimetal l9 has one end secured to the support It by welding or the like in such a manner that its free end, when the lamp is cold, is pressed into contact with the is shown as coiled type, is mounted on the ends of a pair of lead wires 2! and 22 which are held in position by a glass bead 23. The other end of the lead wire 2| is welded to the leading-in wire l4 and the other end of the lead wire 22 is welded to the contact wire I! at a point between the press and the part contacted by the bimetal IS. The proportion of the parts are such that the mounted filament 20 lies parallel to the supports [6 and I8, midway between them but in a higher plane and the bimetal strip l9 extendsbetween the supports it and I8 beneath the filament 20 and with its fiat side close to and exposed to the heat radiated therefrom,

When the external circuit leading to the leading-in wires l4 and i5 is closed the circuit through the filament is completed from the leading-in wire I by way of the lead wire 2|, filament 20, lead wire 22, wire l'l, bimetal strip' i9 back to the lead-Yin wire l5. The heat from the energized filament causes the bimetal strip to bend out of contact with the support 18 thereby breaking the circuit through the filament. lAS the filament 20 is then de-energized the bimetal strip l9 cools down and bends to make contact with the arm l8, again completing the circuit. This energization and de-energization of the filament proceed automatically as long as the external circuit is maintained closed.

The lamp described is of simple, rugged and reliable construction and is readily manufactured. When used in installations where energizaton by batteries is desired and where size, weight and perod of life of the batteries are an important factor, as in connection with life preservers and the like, the longer period of operation provided by the automatically flashing lamp is an important consideration.

The time period of "ofi and on for the filament can be determined largely by the character of the bimetal strip used and by its initial setting. While the arrangement shown with the bimetal beneath the filament is desirable from the point of view that it is not intruded into the Path of the light radiation my invention is not necessarily limited thereto. If the character and proportions of the bimetal is such that the upward bending caused by the heat of sealing the lamp creates the danger of breaking the filament during manufacture, it is desirable to arrange the parts so that on heating it bends away from the filament.

What I claim as new and desire to secure by f Letters Patent of the United States is:

1. An electriclamp comprising a sealed glass bulb provided at one end with a pair of external contacts, a pair of lead wires sealed into the bulb wall and connected to the contacts, one of the lead wires projecting into the bulb and having its 5 end bent at right angles to the longitudinal axis thereof, a contact wire projecting into the bulb and having its free end bent and lying parallel to and spaced laterally from the bent end of the said one lead wire, a filament extending laterally of 1 the bulb axis and supported by and electrically connected to the' other lead-in wire and to the said contact wire respectively, a fiat bimetal strip having one end secured to one of the said bent ends and arranged with its fiat side adjacent to bulb provided at one end with a pair of external contacts, a pair of lead wires sealed into the bulb wall and connected to the contacts, one of the lead, wires projecting into the bulb and having its end bent at right angles to the longitudinal axis thereof. a contact wire projecting into the bulb and having its free end bent and lying parallel to and spaced laterally from the bent end of the said one lead wire, a filament extending laterally of the bulb axis parallel to the said bent ends and supported by and electrically connected to the other lead-in wire and to the said contact wire respectively, a fiat bimetal strip having one end secured to one of the said bent ends and arranged with its fiat side adjacent to the filament and with its free end making contact with the other bent end when the filament is de-energized.

3. An electric lamp comprising a sealed glass bulb provided at one end with a pair of external contacts, a pair of lead wires sealed into the bulb wall and connected to the contacts, one of the lead wires projecting into the bulb and having its end bent at right angles to the longitudinal axis thereoi, a contact wire projecting into the bulb and having its free end bent and lying paiallel to and spaced laterally from the bent end of the said one lead wire, a filament mounted on the ends of a pair of filament support wires which have their other ends secured to the other lead-in wire and to the said contact wire respectively, a fiat bimetal strip having one end secured to one of the said bent ends andarranged with its flat side adjacent to the filament and with its free end making contact with the other bent end when the filament is de-energized.

4. An electric lamp comprising a sealed glass bulb with a re-entrant glas stem, a pair of leadin wires sealed into the stem. a contact wire extending from said stem. one of the lead-in wires and the contact wire extending towards the center of the bulb and having their ends bent to extend parallel to one another and spaced apart, a filament unit consisting of a pair of filament support wires mounted in a glass bead intermediate the ends thereof and a filament extending across the leads at one end, said filament support wires having their other ends secured to the other lead-in wire and to the contact wire respectively in such a manner that the filament is located parallel to the said bend-intermediate thereof, but spaced farther away from the stem, a flat strip of bimetal having one end secured to one of the bent ends in such a manner that its fiat side is exposed to radiation from the filament and its other end makes contact with the other bent end when the filament is de-energized and separates from the said other bent end when the filament is energlzed.

WILLIAM F. MACGREGOR. 

